The L2C leukemia is a B cell leukemia of inbred strain 2 guinea pigs. These cells have surface IgM and C3 receptors. Studies have shown that these leukemia cells possess a strong tumor spcific transplantation antigen (TSTA) that can easily be demonstrated by immunization protection tests in syngeneic animals. A new procedure for extracting the TSTA has been employed using butanol extraction of the L2C cells. The concentrated butanol extract is then precipitated with 5% trichloracetic acid and the supernatant again concentrated and put onto a chromatafocusing column. A 12,000 m.w. fraction is obtained with a pI of 10 that is immunogenic; 1% PAGE idicates this material is composed of two closely placed bands. Amino acid composition and sequence analysis of this band are now in progress. In addition to the above, immunotherapeutic studies of the L2C leukemia are being performed. First administration of a conjugate of ricin to a monoclonal antibody to the surface IgM idiotype produces a significant increase in life span in leukemia animals and about 30% of animals are cured. Second the administration of low dose interluekin-2 (IL-2) therapy produce significant increase in survival of leukemic animals. Both local and systemic administration of LAK cells and IL-2 also produced signifcant prolongation of life. However, in contrast to the results with immunotoxin, no long term cures were produced.